Lily Allen has sparked rumours she may be pregnant after she left a party early and refused to drink alcohol.

The singer has made no secret of her desire to start a family in the near future. She recently confirmed she is taking a break from the music industry to concentrate on her relationship with builder Sam Cooper.

Lily is known for her hard-partying ways, but surprised guests at a party held at the Glastonbury music festival this weekend by leaving early. The star was a guest at the Playstation 3 Singstar event, but rejected all offers of a drink and didn't smoke a cigarette while there. Her decision to wear a figure-concealing poncho also raised eyebrows.

"Lily's behaviour was just so out of character," a source told British newspaper The Sunday Mirror. "Everyone was gossiping that Lily must be pregnant. It was the talk of the party."

The 25-year-old eventually left the event early, telling people she was too tired to stay.

Last month, Lily said settling down and starting a family was "more her goal" than releasing a new album.

The star fell pregnant while dating Chemical Brothers star Ed Simons, but miscarried in 2008. She has spoken of how badly it affected her, admitting she became depressed and had to seek professional help.